Susi Martinez has a great stack of miniatures on her blog including this tutorial to build a teeny tiny (dollhouse scale) aloe plant. The blog text is in Spanish but you can hit http://translate.google.com if you need. I found the pictures pretty self explanatory.
The tutorial uses cold porcelain or air dry clay and then paint but you could, of course, use oven bake polymer clay. I’d go with a fairly translucent green to get the neat waxy shade I find most aloe plants have.